The Physic Garden - Drafting out a Novel

I have (three cheers!) finished the first full draft of my new novel, The Physic Garden. But there's an odd phenomenon with this one and I remember it happening before with - I think - The Curiosity Cabinet. Normally my advice to any writer embarking on a full length novel for the first time would be to write at length and then set about pruning and polishing. It's invariably easier to cut than it is to 'pad things out' - a process which is generally deemed to be inadvisable. On the whole, I agree. However - in this instance, something else has happened and I think I would compare it to the way in which an artist 'blocks out' a picture. I have written about 70,000 words, but I suspect that the finished novel will be a good deal longer, at perhaps 85,000 or even more.
Somebody on a Writers' Message Board of which I'm a member, was asking about recommended novel length the other day. She had been told that 100,000 words, no more, no less was the recommended word count, which seems a mite prescriptive to me. The consensus was that it tended to be 'horses for courses'. If you are Penny Vincenzi you can get away with writing at extreme length (and she does it so very well.) But most of the published novelists among us tended to think that anything between 80,000 and 100,000 was about right with some genres demanding fewer and some demanding more.
And yes, normally, it's much better to write at length and then make your cuts.
But sometimes there needs to be another stage in the process and I think that's the one I've just completed. I needed to gallop through the whole thing for various reasons. One was to get to know my characters and try to understand what seems to me to be quite a complicated set of relationships. Another was to see if the plot actually hung together. And a third reason (this being a historical novel set in Glasgow in the early 1800s) was to find out what I didn't know. Quite a lot as it turned out. One of the pitfalls of writing historical fiction is that the research tends to dominate - you become so fond of your discoveries that they become an end in themselves and the result is heavy handed fictionalised history. Paradoxically, one way of avoiding this is to tell the story and find out what you (and the reader) really need to know. The result is often that you know more than you need to about some things and less than you need to about others. But once the story is blocked out, you can see exactly what you need to know to push the story forward.
All of which goes to explain why this first draft is a wee bit shorter than I would have expected. I can almost guarantee that the next draft will run to about 100,000 words. And then it will be pruned down quite drastically.
Which sounds like a lot of work - but for me, this is the really enjoyable bit. I like revising much more than getting that first draft down. It's like having a framework to hang onto while you venture out into the unknown and I love it!
More as it happens.